Hard gel and soft gel were formed over a fixed region of ternary systems composed of dioctadecyldimetyl ammonium chloride (DOAC), polyols and oils. (1) When soft gels were diluted with water, very stable emulsions were obtained. (2) Relationships between hardness of soft gels and gel composion, temperature were investigated. (3) Structures of soft gels were studied with a differential scanning calorimeter, a X-ray diffractometer and a microscope by polarized light.
Hard gel showed a liquid crystalline structure. But no liquid crystalline structure was observed in oil-riched soft gel (the composition: DOAC 2-3%, glycerin 20-60% and oil 37-78%).
On the other hand, two-component system of DOAC and glycerin (the range of the weight ratio of 5/95 to 50/50) showed a characteristic of liquid crystalline structure.
Size of oil droplets was determined to be 0.4-1.5μm from a frozen electron microscopy of the above soft gel, and the size did not change by the dilution of gel by water.
It is suggested from the above observations that the soft gel which gives a very stable emulsion by the dilution and shows no liquid crystalline structure is composed of micro-oil droplets surrounded by disordered liquid crystal of DOAC and glycerin.